为啥这个自定义 UIView 代码不显示 UILabel 的？

Posted 2023-03-13

【中文标题】为啥这个自定义 UIView 代码不显示 UILabel 的？

【英文标题】：why does this custom UIView code not display the UILabel's?为什么这个自定义 UIView 代码不显示 UILabel 的？

【发布时间】：2011-03-25 01:44:36

【问题描述】：

我有点想知道为什么，当我使用此自定义 UIView 显示一行 3 x UILabels 时，虽然我看到框架的红色轮廓，但在框架内看不到任何东西。那就是标签没有出现，我设置的 UILabel 的黑色边框也没有出现。

任何人都可以在这里发现问题吗？

#import <UIKit/UIKit.h>
@interface LabelRowView : UIView 
    UILabel *_dateLabel;
    UILabel *_titleLabel;
    UILabel *_locationLabel;

@property (nonatomic, retain) UILabel *dateLabel;
@property (nonatomic, retain) UILabel *titleLabel;
@property (nonatomic, retain) UILabel *locationLabel;
- (void)setFont:(UIFont *)newFont;
- (void)setDataWithDate:(NSString*)dateStr AndTitle:(NSString*)titleStr AndLocation:(NSString*)locationStr;
@end

// ==============================================================

@implementation LabelRowView
    @synthesize dateLabel = _dateLabel;
    @synthesize titleLabel = _titleLabel;
    @synthesize locationLabel = _locationLabel;

- (void)setDefaultsForLabel:(UILabel*)label 
    label.layer.borderColor = [UIColor blackColor].CGColor;
    label.layer.borderWidth = 1.0;
    label.textAlignment = UITextAlignmentLeft;
    label.lineBreakMode = UILineBreakModeTailTruncation;
    label.opaque = YES;   // TODO: put back in for performance reasons if possible
    label.backgroundColor = [UIColor clearColor];


- (id)initWithFrame:(CGRect)frame 
    self = [super initWithFrame:frame];
    if (self) 
        // Initialization code
        self.dateLabel      = [[[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, 10, 10)] autorelease];       // Position will be updated later
        self.titleLabel     = [[[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, 10, 10)] autorelease];       // Position will be updated later
        self.locationLabel  = [[[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, 10, 10)] autorelease];       // Position will be updated later

        // Set Defaults
        [self setDefaultsForLabel:self.dateLabel];
        [self setDefaultsForLabel:self.titleLabel];
        [self setDefaultsForLabel:self.locationLabel];

        self.layer.borderColor = [UIColor redColor].CGColor;
        self.layer.borderWidth = 1.0;
    
    return self;


- (void)setDataWithDate:(NSString*)dateStr AndTitle:(NSString*)titleStr AndLocation:(NSString*)locationStr 
    self.dateLabel.text = dateStr;
    self.titleLabel.text = titleStr;
    self.locationLabel.text = locationStr; 


- (void)setFont:(UIFont *)newFont 
    self.dateLabel.font = newFont;
    self.titleLabel.font = newFont;
    self.locationLabel.font = newFont;


- (void)layoutSubviews 
    [super layoutSubviews];
        // Get current width for this subview 
        CGFloat contentViewWidth = self.frame.size.width;
        CGSize maximumLabelSize = CGSizeMake(contentViewWidth, 9999);  
        CGFloat oneLineHeight = [@"A" sizeWithFont:self.dateLabel.font constrainedToSize:maximumLabelSize lineBreakMode:UILineBreakModeTailTruncation].height;

        // Calculate Widths
        CGFloat dateColumnWidth = [@"Ddd 12:22 " sizeWithFont:self.dateLabel.font constrainedToSize:maximumLabelSize lineBreakMode:UILineBreakModeTailTruncation].width;
        CGFloat titleColumnWidth = (contentViewWidth - dateColumnWidth) * 2.0/3.0;
        CGFloat locationColumnWidth = contentViewWidth - dateColumnWidth - titleColumnWidth;

        // Date - Layout 
        CGRect newRect = CGRectMake(0.0, 0.0, dateColumnWidth, oneLineHeight);
        self.dateLabel.frame = newRect;

        // Date - Layout 
        newRect = CGRectMake(dateColumnWidth, 0.0, titleColumnWidth, oneLineHeight);
        self.titleLabel.frame = newRect;

        // Title - Layout 
        newRect = CGRectMake(dateColumnWidth + titleColumnWidth, 0.0, locationColumnWidth, oneLineHeight);
        self.locationLabel.frame = newRect;


- (void)dealloc

    [super dealloc];


@end

【参考方案1】：

您似乎没有将 UILabel 添加为子视图。

【讨论】：

doh - 感谢 Arkku，我一直在忽略这一点，因为我一直在查看它 - 检查了从根控制器向下通过层次结构的所有 addSubview，但忘记了叶节点处的那个 :)